media/audio/pulse/pulse_output.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4 //
   5 // Creates an audio output stream based on the PulseAudio asynchronous API;
   6 // specifically using the pa_threaded_mainloop model.
   7 //
   8 // If the stream is successfully opened, Close() must be called before the
   9 // stream is deleted as Close() is responsible for ensuring resource cleanup
  10 // occurs.
  11 //
  12 // This object is designed so that all AudioOutputStream methods will be called
  13 // on the same thread that created the object.
  14 //
  15 // WARNING: This object blocks on internal PulseAudio calls in Open() while
  16 // waiting for PulseAudio's context structure to be ready.  It also blocks in
  17 // inside PulseAudio in Start() and repeated during playback, waiting for
  18 // PulseAudio write callbacks to occur.
  19
  20 #ifndef MEDIA_AUDIO_PULSE_PULSE_OUTPUT_H_
  21 #define MEDIA_AUDIO_PULSE_PULSE_OUTPUT_H_
  22
  23 #include <string>
  24
  25 #include "base/memory/scoped_ptr.h"
  26 #include "base/threading/thread_checker.h"
  27 #include "media/audio/audio_io.h"
  28 #include "media/audio/audio_parameters.h"
  29
  30 struct pa_context;
  31 struct pa_operation;
  32 struct pa_stream;
  33 struct pa_threaded_mainloop;
  34
  35 namespace media {
  36 class AudioManagerBase;
  37
  38 class PulseAudioOutputStream : public AudioOutputStream {
  39  public:
  40   PulseAudioOutputStream(const AudioParameters& params,
  41                          const std::string& device_id,
  42                          AudioManagerBase* manager);
  43
  44   ~PulseAudioOutputStream() override;
  45
  46   // Implementation of AudioOutputStream.
  47   bool Open() override;
  48   void Close() override;
  49   void Start(AudioSourceCallback* callback) override;
  50   void Stop() override;
  51   void SetVolume(double volume) override;
  52   void GetVolume(double* volume) override;
  53
  54  private:
  55   // Called by PulseAudio when |pa_stream_| change state.  If an unexpected
  56   // failure state change happens and |source_callback_| is set
  57   // this method will forward the error via OnError().
  58   static void StreamNotifyCallback(pa_stream* s, void* p_this);
  59
  60   // Called by PulseAudio when it needs more audio data.
  61   static void StreamRequestCallback(pa_stream* s, size_t len, void* p_this);
  62
  63   // Fulfill a write request from the write request callback.  Outputs silence
  64   // if the request could not be fulfilled.
  65   void FulfillWriteRequest(size_t requested_bytes);
  66
  67   // Close() helper function to free internal structs.
  68   void Reset();
  69
  70   // AudioParameters from the constructor.
  71   const AudioParameters params_;
  72
  73   // The device ID for the device to open.
  74   const std::string device_id_;
  75
  76   // Audio manager that created us.  Used to report that we've closed.
  77   AudioManagerBase* manager_;
  78
  79   // PulseAudio API structs.
  80   pa_context* pa_context_;
  81   pa_threaded_mainloop* pa_mainloop_;
  82   pa_stream* pa_stream_;
  83
  84   // Float representation of volume from 0.0 to 1.0.
  85   float volume_;
  86
  87   // Callback to audio data source.  Must only be modified while holding a lock
  88   // on |pa_mainloop_| via pa_threaded_mainloop_lock().
  89   AudioSourceCallback* source_callback_;
  90
  91   // Container for retrieving data from AudioSourceCallback::OnMoreData().
  92   scoped_ptr<AudioBus> audio_bus_;
  93
  94   base::ThreadChecker thread_checker_;
  95
  96   DISALLOW_COPY_AND_ASSIGN(PulseAudioOutputStream);
  97 };
  98
  99 }  // namespace media
 100
 101 #endif  // MEDIA_AUDIO_PULSE_PULSE_OUTPUT_H_